 /*******************************************************************************
  * Copyright (c) 2005, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/

 package org.eclipse.core.commands;

 import java.util.HashMap ;
 import java.util.Map ;
 import java.util.Set ;

 import org.eclipse.core.commands.common.NamedHandleObject;
 import org.eclipse.core.commands.common.NotDefinedException;

 /**
  * <p>
  * A named handle object that can carry state with it. This state can be used to
  * override the name or description.
  * </p>
  * <p>
  * Clients may neither instantiate nor extend this class.
  * </p>
  *
  * @since 3.2
  */
 abstract class NamedHandleObjectWithState extends NamedHandleObject implements
         IObjectWithState {

     /**
      * An empty string array, which can be returned from {@link #getStateIds()}
      * if there is no state.
      */
     private static final String [] NO_STATE = new String [0];

     /**
      * The map of states currently held by this command. If this command has no
      * state, then this will be <code>null</code>.
      */
     private Map states = null;

     /**
      * Constructs a new instance of <code>NamedHandleObject<WithState/code>.
      *
      * @param id
      * The identifier for this handle; must not be <code>null</code>.
      */
     protected NamedHandleObjectWithState(final String id) {
         super(id);
     }

     public void addState(final String stateId, final State state) {
         if (state == null) {
             throw new NullPointerException ("Cannot add a null state"); //$NON-NLS-1$
 }

         if (states == null) {
             states = new HashMap (3);
         }
         states.put(stateId, state);
     }

     public final String getDescription() throws NotDefinedException {
         final String description = super.getDescription(); // Trigger a NDE.

         final State descriptionState = getState(INamedHandleStateIds.DESCRIPTION);
         if (descriptionState != null) {
             final Object value = descriptionState.getValue();
             if (value != null) {
                 return value.toString();
             }
         }

         return description;
     }

     public final String getName() throws NotDefinedException {
         final String name = super.getName(); // Trigger a NDE, if necessary.

         final State nameState = getState(INamedHandleStateIds.NAME);
         if (nameState != null) {
             final Object value = nameState.getValue();
             if (value != null) {
                 return value.toString();
             }
         }

         return name;
     }

     public final State getState(final String stateId) {
         if ((states == null) || (states.isEmpty())) {
             return null;
         }

         return (State) states.get(stateId);
     }

     public final String [] getStateIds() {
         if ((states == null) || (states.isEmpty())) {
             return NO_STATE;
         }

         final Set stateIds = states.keySet();
         return (String []) stateIds.toArray(new String [stateIds.size()]);
     }

     public void removeState(final String id) {
         if (id == null) {
             throw new NullPointerException ("Cannot remove a null id"); //$NON-NLS-1$
 }

         if (states != null) {
             states.remove(id);
             if (states.isEmpty()) {
                 states = null;
             }
         }
     }

 }

